Service history analysis and teardown evidence - Key elements for structural usage monitoring of an ageing fleet

Abstract

Various elements are combined in this paper to demonstrate a credible basis for structural usage monitoring of the mixed fleet of ageing VC10 aircraft. Practical teardown findings are used to substantiate the theoretical assessment of the aircraft in terms of historic and current flight profiles. Problems with limited or incomplete records for early usage of the VC10 aircraft are overcome to account for both commercial and military service. The results of all of these elements in combination with fatigue and damage tolerance calculations are presented. An approach developed using NzW principles is shown to provide a reliable basis for structural usage monitoring of the VC10 fleet. From the combined results, a Limit of Validity (LOV) is derived for the critical wing root joint on each aircraft. This represents the point at which a programme of inspection and bolt replacements would be necessary to satisfy damage tolerance requirements. Consequently it is possible to determine the remaining margins with respect to the LOV and ensure that they are sufficient to enable the expected retirement dates to be achieved within those limits. © Springer Science+Business Media B.V. 2009.